Before the Strong Force: Rethinking Nuclear Interactions

Author: Denis Avetisyan

A 1969 paper proposed that electromagnetic fluctuations and plasma formation could explain the forces binding atomic nuclei, offering a radical alternative to emerging strong interaction theories.

Barry Ninham established the Department of Applied Mathematical Physics at the Australian National University in 1970, laying the groundwork for future research in a field perpetually balancing theoretical elegance with the inevitable realities of practical application.

This historical review examines B.W. Ninham and C. Pask’s exploration of electromagnetic mechanisms for nucleon interactions and pion behavior, predating widespread acceptance of the Standard Model.

The prevailing strong interaction models of the mid-20th century necessitated ad-hoc coupling constants to explain nucleon interactions, prompting exploration of alternative frameworks. This is the central premise of “Observations on the possible electromagnetic nature of nucleon interactions and pions” — historical manuscript from 1969 by B. W. Ninham and C. Pask, which proposes a radically different approach rooted in quantum electrodynamics. The manuscript posits that nuclear forces and pion behavior can emerge from electromagnetic fluctuations and the formation of a transient electron-positron plasma, eliminating the need for arbitrary strong interaction parameters and offering a calculated pion mass and lifetime. Could a purely electromagnetic description of nuclear phenomena ultimately provide a more fundamental understanding of matter’s strong force?

The Limits of Theory: When Elegance Breaks Down

The predictive power of classical physics, so effective in describing everyday experiences and even celestial mechanics, breaks down when examining the realm of the very small. At the atomic and subatomic scales, phenomena like the discrete spectra of emitted light and the stability of matter itself defy classical explanation. This necessitated the development of quantum mechanics, a fundamentally different framework governed by principles such as Planck Quantisation – the idea that energy isn’t continuous, but exists in discrete packets, or quanta. This quantization isn’t merely a mathematical trick; it reflects a core property of the universe at these scales, where energy, momentum, and other quantities are granular rather than fluid. Consequently, a complete understanding of matter and its interactions requires abandoning the continuous models of classical physics in favor of this probabilistic, quantized description of reality.

The very structure of physical theories is fundamentally constrained by the principle of causality, which dictates that an effect cannot precede its cause. This seemingly intuitive rule has profoundly shaped the development of Quantum Electrodynamics (QED). Early attempts to formulate quantum field theories often resulted in predictions of infinite probabilities and unphysical negative energies, violating causality and rendering the theories unusable. To resolve these issues, physicists implemented techniques like renormalization and carefully constructed the mathematical framework of QED to ensure that interactions propagate forward in time, adhering to the causal order. Essentially, the success of QED isn’t merely due to its predictive power, but also to its internal consistency with this fundamental principle; any viable theory attempting to expand upon QED, or address phenomena beyond its scope, must also rigorously uphold the tenets of causality to remain physically meaningful.

Quantum Electrodynamics, while extraordinarily precise in its predictions – notably the minute energy difference known as the Lamb Shift – ultimately describes how forces manifest, not their fundamental origin. The theory successfully models interactions via the exchange of photons, but leaves unanswered the question of why these forces exist in the first place. A proposed theoretical framework seeks to move beyond this descriptive power, focusing specifically on the strong force-the interaction binding quarks within protons and neutrons, and ultimately holding atomic nuclei together. This new approach posits a different mechanism for force generation, moving beyond the reliance on force-carrying particles and instead exploring the potential of underlying geometrical structures and emergent properties of spacetime to account for the observed interactions, potentially unifying the strong force with other fundamental interactions in a more complete picture of the universe.

A Radically Simple Force: Electromagnetism as the Core

The Ninham-Pask theory postulates that the strong nuclear force, responsible for binding nucleons within the atomic nucleus, is not a fundamental force distinct from electromagnetism, but rather an emergent phenomenon arising from electromagnetic interactions. This hypothesis extends to the pion, a meson mediating the strong force, suggesting it too originates from electromagnetic processes rather than requiring a separate strong interaction mechanism. The theory posits that specific electromagnetic configurations and boundary conditions within nucleons lead to an effective attractive force resembling the strong nuclear force, and that the pion’s properties are a direct consequence of these electromagnetic origins. This approach differs significantly from standard models relying on the exchange of gluons and quarks, offering a purely electromagnetic explanation for nuclear binding.

The Ninham-Pask theory posits that the strong nuclear force originates from electromagnetic interactions, building directly upon established principles of Electromagnetic Theory. This approach proposes a unification of fundamental forces by describing the nuclear force as a manifestation of electromagnetic phenomena rather than requiring a separate strong force interaction. A key quantitative prediction of the model is a pion mass equivalent to approximately 220 electron masses; this value serves as a testable prediction differentiating it from standard models which calculate the pion mass using more complex quantum mechanical approaches and differing values. This calculated pion mass is a direct consequence of the specific electromagnetic configurations proposed within the theory.

The Ninham-Pask theory presents a departure from standard models of the strong nuclear force, which rely heavily on quantum chromodynamics and the exchange of gluons. Current quantum mechanical explanations, while successful in many predictions, encounter challenges when reconciling the force’s behavior at different energy scales and in certain nuclear configurations. By positing an electromagnetic origin for the nuclear force, the theory offers a potential pathway to address these discrepancies, suggesting that the force arises from interactions between charged constituents within nucleons, rather than a dedicated strong force carrier. This approach aims to provide a more unified framework, potentially simplifying calculations and offering novel insights into nuclear structure and stability where current models exhibit limitations.

Bridging the Gap: Semiclassical Refinements and Precise Calculation

Semiclassical electrodynamics extends the Ninham-Pask theory by integrating classical electromagnetic principles with quantum mechanical considerations. The Ninham-Pask theory initially described interactions based purely on classical polarisability; however, semiclassical refinements introduce quantum effects, such as vacuum fluctuations and zero-point energy, into the electromagnetic field calculations. This integration allows for the treatment of interactions involving particles that do not possess a net electric charge, and provides a more complete description of electromagnetic forces at the molecular level. The framework allows calculations beyond those possible with purely classical models, offering insights into phenomena where both classical and quantum behaviors are significant.

Accurate calculation of electromagnetic forces within the semiclassical framework fundamentally depends on quantifying molecular polarisability. Polarisability, a measure of how easily the electron cloud of a molecule is distorted by an electric field, directly influences the strength of induced dipole moments. These induced dipoles are the primary source of attractive or repulsive forces between molecules, and their magnitude is proportional to both the electric field strength and the molecular polarisability α. Therefore, precise knowledge of α for the interacting molecules is essential for correctly determining the electromagnetic force, as even small variations in polarisability can significantly impact the calculated interaction energy and resulting force vectors.

The Mahanty-Ninham Electromagnetic Vector Equation represents a refinement of earlier work, enabling the calculation of electromagnetic forces acting on uncharged neutrons. This expansion of the theory’s scope posits that neutron interactions are mediated by electromagnetic forces, rather than solely by nuclear forces. Calculations based on this equation predict an interaction temperature of approximately 140 me $c^2$ , a value derived from assuming an effective nuclear interaction distance of 1 femtometer (fm). This predicted temperature provides a quantitative metric for the strength of the electromagnetic interaction within the model and allows for comparisons with experimental data regarding neutron behavior.

From Empty Space to Tangible Forces: The Electromagnetic Landscape

The Casimir Effect stands as a compelling validation of quantum electrodynamics, demonstrating that even in the complete absence of charge, a measurable force exists between closely spaced, uncharged conducting plates. This arises from the restriction of vacuum fluctuations of the electromagnetic field; only certain wavelengths of virtual photons can exist within the confined space, leading to a pressure differential. Essentially, the plates are pushed together by the external atmospheric pressure of the quantum vacuum. Initial calculations predicted this force, but its experimental confirmation in 1997 – measuring an attractive force consistent with theoretical predictions – provided strong empirical support for the idea that empty space isn’t truly empty, but rather teeming with fleeting electromagnetic activity. The effect isn’t merely a theoretical curiosity; it has implications for nanotechnology, where these forces become significant at small scales and must be accounted for in the design of micro- and nano-electromechanical systems.

While the Casimir Effect initially focused on the attractive force between closely spaced, perfectly conducting plates, Lifshitz Theory broadened this understanding to encompass a far wider range of materials and geometries. This refinement moves beyond idealized conditions by accounting for the dielectric properties of the interacting bodies, enabling calculations of van der Waals forces between any two materials – whether metals, dielectrics, or semiconductors. Crucially, Lifshitz Theory doesn’t just predict whether a force exists, but also its magnitude and, importantly, its sign; it demonstrates that the force can be attractive or repulsive depending on the materials’ optical properties and separation distance. This expanded framework is essential for understanding phenomena ranging from colloidal stability and adhesion to the behavior of nanoscale devices, providing a more nuanced and accurate depiction of interfacial forces than previously possible.

The Dzyaloshinskii-Lifshitz-Pitaevskii (DLP) theory represents a significant advancement in understanding interfacial forces by explicitly incorporating the dielectric susceptibility of materials. Unlike earlier models, DLP recognizes that a material’s response to an electric field profoundly influences the van der Waals interaction. This refinement allows for substantially more accurate calculations of forces between diverse materials, moving beyond the simplified metallic plate scenario of the original Casimir effect. The theory’s predictive power extends even to seemingly unrelated phenomena; for instance, calculations based on DLP predicted a neutral pion lifetime of no more than $1.5 \times 10^{-{17}}$ seconds, a result that, while differing from the experimentally measured value of $(0.84 \pm 0.1) \times 10^{-{16}}$ seconds, demonstrates the theory’s capacity to connect seemingly disparate areas of physics and provide quantitative benchmarks for further refinement.

Beyond the Standard Model: A Universe Governed by Electromagnetism?

The universe’s fundamental forces, long understood through the Standard Model, exhibit a surprisingly intricate relationship when examined at the quantum level. Investigations into weak interactions – responsible for certain types of radioactive decay and crucial to stellar processes – demonstrate they are not truly separate from electromagnetism, but rather facets of a single, more comprehensive electroweak force. This connection, revealed through the work of Glashow, Salam, and Weinberg, suggests that what appears as distinct forces at everyday energies are, in fact, unified under specific conditions. The interplay between these forces isn’t simply additive; rather, they ‘mix’ and influence each other, altering particle behavior and requiring physicists to consider the combined effects when predicting outcomes. This complex choreography underscores the interconnectedness of the universe’s building blocks and hints at deeper, yet undiscovered, symmetries governing reality.

The muon, often described as a ‘heavy electron’, presents a compelling case for refining existing electromagnetic models. While sharing many properties with the electron – both are fundamental leptons with a spin of 1/2 and interact via the electromagnetic force – the muon’s significantly larger mass, approximately 207 times that of the electron, introduces discrepancies when predicted solely through the standard model. These deviations aren’t merely quantitative; they suggest that a complete understanding of electromagnetic interactions requires accounting for the diverse masses and properties of all elementary particles, not just the electron. The muon’s behavior, and that of other heavier leptons like the tau, demonstrates that electromagnetic interactions aren’t universally experienced in the same way, necessitating a more nuanced and inclusive theoretical framework to accurately describe the full spectrum of particle behavior and their interactions within the universe.

Current models of particle physics, while remarkably successful, leave certain phenomena unexplained, hinting at a deeper, more fundamental role for electromagnetic interactions. Investigations into the strong nuclear force, responsible for binding protons and neutrons, reveal unexpected connections to electromagnetism, particularly when considering particles like the pion. Theoretical calculations, based on extending the influence of electromagnetic forces, predicted a pion mass of roughly 220 electron masses – a figure strikingly close to the experimentally determined value of approximately 270 electron masses. This congruence suggests that electromagnetism isn’t simply one force among many, but potentially a foundational component underlying the very structure of matter and the forces governing it, offering a pathway toward a more unified and complete understanding of the universe at its most basic level.

The pursuit of elegant theories explaining nucleon interactions, as posited in this manuscript, inevitably encounters the brutal reality of production environments. This paper’s exploration of electromagnetic explanations for nuclear forces, bypassing traditional strong interaction models, feels… optimistic. As Isaac Newton observed, “I do not know what I may seem to the world, but to myself I seem to be a boy playing on the seashore.” The inherent complexity of fluctuating electromagnetic fields and the formation of electron-positron plasmas-the very mechanisms proposed to explain pion interactions-will, undoubtedly, reveal unforeseen edge cases. Any perceived self-consistency is merely a temporary reprieve; a system hasn’t broken yet, but it will. Documentation, in such a venture, serves only to meticulously record the points of future failure.

Loose Ends and Static

The proposition that nucleon interactions might yield to electromagnetic accounting, bypassing the need for entirely new fundamental forces, remains… a persistent ghost in the machine. The Ninham and Pask work, while elegantly sidestepping certain complexities of the strong interaction, rests on a foundation of calculated fluctuations. Tests are, after all, a form of faith, not certainty, and the subtle dance of virtual particle pairs is notoriously sensitive to boundary conditions – conditions production systems are always eager to redefine. The presumed plasma state, a necessary component of this model, feels less like a prediction and more like a convenient assumption to smooth over the gaps.

Future explorations will inevitably focus on refining the parameters of these fluctuations, attempting to reconcile theoretical predictions with increasingly precise measurements of nuclear forces. The search for observable Casimir-like effects within nuclear matter, or perhaps subtle anomalies in pion scattering, might offer a glimpse of validation. However, one suspects that any ‘proof’ will be accompanied by a new set of intractable problems. The universe rarely offers clean victories.

Ultimately, the value of this approach may not lie in its ultimate correctness, but in its insistence on revisiting first principles. The history of physics is littered with abandoned frameworks, each a stepping stone to the next, more complicated, mess. Automation will not save anyone, but a healthy skepticism, and a willingness to re-examine even the most fundamental assumptions, might just delay the inevitable Monday morning crash.

Original article: https://arxiv.org/pdf/2602.06058.pdf

Contact the author: https://www.linkedin.com/in/avetisyan/